1. Little to no end user interruption
2. No loss of email connectivity
3. All work must be done by internal IT staff
4. No third party tools can be used
1 NT4 PDC in NYK and 1 NT4 BDC in Switzerland. Two Exchange 5.5 servers in NYK, one in Switzerland and one in Hong Kong. There are also various software packages that sit on top of the Exchange infrastructure that must remain intact, such as RightFax (email faxing), Goodlink (mobile email) etc. Exchange is installed on member servers, none of the Exchange servers are installed on a PDC/BDC.
2003 Active Directory Domain with Exchange 2003 Enterprise Edition. Exchange servers will be in two-server clusters. 4 hub offices will house the Exchange clusters.
In order to accomplish the above design goals and satisfy all the requirements, taking into account the existing network infrastructure, the following design should prove to be successful.
First, we will install a new server into our existing NT4 domain and make it a BDC for the domain. We will then, promote the new BDC to a PDC and allow time for replication. Once replication is complete, we will take the old PDC offline (by unplugging network connection or shutting down). We will then upgrade the new NT4 PDC to Server 2003 and run DCPROMO to install Active Directory. This process should preserve all existing user accounts, machine accounts, groups, permissions, etc. So far we satisfy all requirements.
Next, we upgrade or replace all existing NT4 BDCs. Once all NT4 servers are removed, we can then upgrade our new Active directory domain to Server 2003 Native Mode. As no more NT4 servers will be participating as domain controllers.
NOTE: During this time, all existing Exchange 5.5 servers will be maintained as NT4 member servers of the 2003 domain. Exchange 5.5 will continue to handle mail for us until the upgrade to Exchange 2003.
Exchange 2003 Migration:
For this part, we will install our first Exchange 2003 server (on a 2003 Enterprise Edition server installed as a member server) into our existing Exchange 5.5 site. To the exchange site, we are just adding a new server. The Exchange deployment tools will walk us through installing the Active Directory Connector and all necessary connection agreements. The SRS will also be installed. One Exchange 2003 server per hub office will be installed initially. Once we verify that the ADC is working properly and the “Move mailbox” wizard is available, all Exchange 5.5 user mailboxes will be moved to an Exchange 2003 server. Once all Exchange 5.5 mailboxes, public folders, distribution lists, custom forms, etc, are replicated over to the new Exchange 2003 servers, the existing Exchange 5.5 servers will be shut down to verify connectivity and that no “behind the scenes” issues exist. Once our Exchange organization has been verified to be functioning correctly with no further references to the Exchange 5.5 servers, we can then begin to de-commission them. This will be done by removing all references to Exchange 5.5 as replication partners on all public folders, and other exchange resources. Then the servers can be deleted from the Exchange 5.5 server administrator.
During this migration process, the only end user interruption noticed will be during the move mailbox process, as users will be logged out of their exchange mailboxes during a mailbox move. Mail flow is not affected since we installed Exchange 2003 into our existing Exchange 5.5 site, so the routing group is the same. The only remaining task to complete is something I left out above. Before Exchange 5.5 can be shut down or de-commissioned, the SMTP connector will need to be moved from one of the Exchange 5.5 servers to one of the Exchange 2003 servers. Once this is complete, and mail flow has been verified, then the Exchange 5.5 servers can be removed.
The end result is a quick, efficient migration/upgrade to Server 2003 and Exchange 2003. A final note here is on Clustering. The reason we did not use our clusters to install the first Exchange 2003 server is that there are certain components of Exchange that will not function on a cluster. Such as the SRS and ADC. This is why we will be using a standalone server in all hub offices for the initial move to Exchange 2003. Once we have Exchange 2003 up and running globally, we can then introduce our Exchange 2003 Clusters and then move mailboxes once more to the clusters. Once finished, the SMTP (bridgehead) can be moved to the appropriate cluster and the initial Exchange 2003 standalone servers can be removed.
The initial plan was to do a parallel migration, basically creating a whole new system in parallel to our existing system. This plan has many problems and would not have worked for us. End users would have received all new machine profiles, outlook profiles would have been lost, etc. This would have created too much work for our internal IT staff and caused too much interruption to end user connectivity. Not to mention mail flow and interoperability with Exchange 5.5 and Exchange 2003 is much more complicated when installed in separate Exchange Organizations. Third party tools would almost certainly be needed to maintain the level of co-existence we would have needed.